Thin-wall housing

Abstract

A fire-resistant polycarbonate resin composition containing A) 5-50 parts by weight of liquid crystal polymer, B) 90-40 parts by weight of polycarbonate resin, C) 2-20 parts by weight of flame retardant, and 0.1-1.0 parts by weight of polytetrafluoroethylene.

We claim: 
     
       1. A fire-resistant thin wall housing comprising a homogeneous polycarbonate resin comprising A) 5-50 parts by weight of a liquid crystal polymer,   B) 90-40 parts by weight of a polycarbonate resin, produced by hot-melt polymerization of an aromatic dihydroxy compound and a diester carbonate, having phenolic and nonphenolic end groups and having an equivalence ratio of phenolic end group (I) and nonphenolic end group (II), (I)/(II), which is greater than 1/19,   C) 2-20 parts by weight of a flame retardant, and   D) 0.1-1.0 part by weight of polytetrafluoroethylene wherein the housing meets a UL-94 flame-retardant standard of at least V-II at a thickness of 1/16 inch and has a flexural modulus at least equal to the flexural modulus of a thin wall housing of substantially the same thickness which contains no flame retardant.     
     
     
       2. The housing of claim 1 wherein flame retardant C) is a phosphate compound. 
     
     
       3. The housing of claim 1 wherein flame retardant C) is a brominated epoxy. 
     
     
       4. The housing of claim 1 wherein flame retardant C) is a brominated polycarbonate. 
     
     
       5. The housing of claim 1 wherein flame retardant C) is a combination of a phosphate and a brominated epoxy or a brominated polycarbonate. 
     
     
       6. The housing of claim 1 wherein the liquid crystal polymer is a thermotropic liquid crystal polyester. 
     
     
       7. The housing of claim 6 wherein the polyester contains segments with the structure --O--R--O--,   --CO--RCO-- or   --O--R--CO-- wherein R is selected from ##STR11##     
     
     
       8. The housing of claim 6 wherein the polyester contains segments with the structure --O--R--O--, --CO--RCO-- or   --O--R--CO-- wherein R is selected from ##STR12## and wherein the aromatic rings, aliphatic groups or alicyclic groups of R are substituted with --BR, --Cl, --COOH, --COHN 2 , --CH 3 , --C(CH3) 3 , ##STR13## or combinations thereof.     
     
     
       9. The housing of claim 1 wherein the equivalence ratio is greater than 1/10. 
     
     
       10. The housing of claim 9 wherein the equivalence ratio is greater than 1/5. 
     
     
       11. The composition of claim 1 wherein the phenolic end group (I) has the formula ##STR14## and the nonphenolic end group (II) has the formula ##STR15## wherein R 1  and R 2  each represent a hydrogen atom, a linear or branched alkyl group with less than 20 carbons, unsubstituted or substituted with halogen atoms. 
     
     
       12. The housing of claim 1 wherein the polycarbonate resin comprises a branched polycarbonate. 
     
     
       13. The housing of claim 1 wherein the diester carbonate is diphenyl carbonate. 
     
     
       14. The housing of claim 1 wherein the aromatic dihydroxy compound is 2,2-bis(4-hydroxyphenyl)propane. 
     
     
       15. The housing of claim 14 wherein the diester carbonate is a combination of carbonates. 
     
     
       16. The housing of claim 14 wherein the diester carbonate is diphenyl carbonate. 
     
     
       17. The housing of claim 1, in which the flame retardant C) is one, or a combination, of a) phosphate compounds, b) brominated epoxies, or c) brominated polycarbonates. 
     
     
       18. A fire-resistant thin wall housing consisting essentially of a homogeneous polycarbonate resin consisting essentially of A) 5-50 parts by weight of a liquid crystal polymer,   B) 90-40 parts by weight of a polycarbonate resin, produced by hot-melt polymerization of an aromatic dihydroxy compound and a diester carbonate, having phenolic and nonphenolic end groups and having an equivalence ratio of phenolic end group (I) and nonphenolic end group (II), (I)/(II), which is greater than 1/19,   C) 2-20 parts by weight of a flame retardant, and   D) 0.1-1.0 part by weight of polytetrafluoroethylene wherein the housing meets a UL-94 flame-retardant standard of at least V-II at a thickness of 1/16 inch and has a flexural modulus at least equal to the flexural modulus of a thin wall housing of substantially the same thickness which contains no flame retardant.     
     
     
       19. The housing of claim 18 which is a computer housing. 
     
     
       20. The housing of claim 18 which is a case for a small portable machine.